The heating of large volumes of water is presently extremely costly, both in terms of the capital cost of the equipment involved, and in terms of the energy costs involved in the heating process.
It has been known in the past to use hot water in the preparation of concrete mixer to act as a trigger in the curing process whereby the curing time is substantially reduced. Since the introduction of chemical accelerators, the use of hot water has been virtually eliminated. However, chemical accelerators are becoming increasingly expensive and their use tends to promote the formation of rust in the reinforcing steel used with the concrete. In fact, the use of calcium chloride above a level of about 0.8%, which is not particularly effective, was recently banned in Australia for this reason. While other curing accelerators are available for use, they are even more expensive than calcium chloride.
The major obstacle preventing a return to the use of hot water to accelerate the concrete curing has been the capital cost and energy cost of heating the water. It will be appreciated that a large volume of water must be heated to satisfy the requirements of a typical concrete batching plant, and since a large heat exchanger must be used to bring the large volume of water to the required temperature over a long period of time, it has not in the past been economically viable to reintroduce the use of hot water for this purpose.